DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company uses Amazon S3 to store large CSV files and runs Amazon Athena queries on them. The queries are becoming slower as data grows. A data engineer suggests converting the files to Apache Parquet format and partitioning the data. What is the primary benefit of converting to Parquet?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Parquet stores data in a columnar format, reducing the amount of data scanned per query.
Parquet is a columnar storage format that stores data by columns rather than rows. When Athena queries only a subset of columns, it can read just those columns from disk, drastically reducing the amount of data scanned per query. This directly addresses the performance slowdown because Athena charges by data scanned, and less scanning means faster queries and lower costs.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Parquet allows schema evolution without rewriting files.
Why it's wrong here
Schema evolution is not a primary benefit of Parquet.
✗
Parquet supports nested data structures that CSV cannot.
Why it's wrong here
While true, it is not the primary benefit for query speed.
✓
Parquet stores data in a columnar format, reducing the amount of data scanned per query.
Why this is correct
Columnar storage minimizes I/O by reading only relevant columns.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Parquet is compressed by default, reducing storage costs.
Why it's wrong here
Compression is a benefit but not the primary query performance benefit.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the general benefits of Parquet (compression, schema evolution, nested data) with the primary performance benefit for Athena, which is columnar pruning reducing scanned data.
Detailed technical explanation
How to think about this question
Under the hood, Parquet uses a row group structure with column chunks, each stored with its own metadata (min/max statistics, dictionary pages). Athena leverages predicate pushdown and column projection to skip entire row groups that don't match filter conditions, and only reads the necessary columns. In a real-world scenario, a 1 TB CSV table with 100 columns can be reduced to scanning just 10 GB per query when converted to Parquet and queried with selective filters, yielding a 100x performance improvement.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Parquet stores data in a columnar format, reducing the amount of data scanned per query. — Parquet is a columnar storage format that stores data by columns rather than rows. When Athena queries only a subset of columns, it can read just those columns from disk, drastically reducing the amount of data scanned per query. This directly addresses the performance slowdown because Athena charges by data scanned, and less scanning means faster queries and lower costs.
What should I do if I get this DEA-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This DEA-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DEA-C01 exam.
Question Discussion
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